Q. When a map is inserted sideways on a verso page, which direction should it face? Should the top of the map be near the gutter or near the outside margin? Is there a standard?
A. The practice at the University of Chicago Press is to rotate the image 90 degrees counterclockwise, which would mean that the top of the map is toward the outside margin on a verso (left-hand) page but toward the middle of the book (the gutter or binding) on a recto (right-hand) page.
A map rotated in this way is called a broadside figure (as defined in the glossary at the end of CMOS). In most books, pages are taller than they are wide, so a broadside figure will usually be in landscape (▭) rather than portrait (▯) orientation before being rotated.